java servlet中上传文件的简单实现（基于第三方jar）

这里的案例使用了两种文件上传的组件、分别介绍

1、使用JSPSmartUpload完成上传

 package test_servlet_package;

 import java.io.File;
 import java.io.IOException;
 import java.util.Calendar;
 import java.util.Random;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import com.jspsmart.upload.SmartUpload;

 public class test_servlet_SmartUpload extends HttpServlet {

     String tempPath = "D:\\test";
     String filePath = "D:\\filePath";
     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         response.setCharacterEncoding("GBK");
         SmartUpload mySmartUpload = new SmartUpload();
         // 初始化
         mySmartUpload.initialize(getServletConfig(), request, response);
         long file_size_max = 4000000;
         String ext = "";
         try {
             mySmartUpload.setAllowedFilesList("jpg,gif,png");
             mySmartUpload.upload();// 上载文件
         } catch (Exception e) {
             response.getWriter().write("<script> alert('只允许上传.jpg和.gif类型图片文件');</script>");
         }
         try {
             com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
             if (!myFile.isMissing()) {
                 ext = myFile.getFileExt(); // 取得后缀名
                 int file_size = myFile.getSize(); // 取得文件的大小
                 String saveurl = "";
                 if (file_size < file_size_max) {
                     // 更改文件名，取得当前上传时间的毫秒数值
                     Calendar calendar = Calendar.getInstance();
                     String filename = String.valueOf(calendar.getTimeInMillis());
                     Random r = new Random();
                     String ram = String.valueOf(r.nextInt(1241241241));
                     filename = filename + ram;
                     filename = filename.substring(0, (filename.length() - ext.length() - 1));
                     //saveurl = this.getServletContext().getRealPath("/") + "/uploadFile/" + filename + "." + ext;
                     //System.out.println(saveurl);
                     File uploadFile2 = new File(filePath);
                     if(!uploadFile2.exists()){
                         uploadFile2.mkdirs();
                     }
                     myFile.saveAs(filePath+"/"+filename+"." + ext);
                 }
             }
             String name = mySmartUpload.getRequest().getParameter("name");
             request.setAttribute("name", "name");
             request.getSession().setAttribute("name", "name");
             request.getSession().getId();
             System.out.println(name);
         } catch (Exception e) {
             e.printStackTrace();
         }
         request.getRequestDispatcher("/uploadsuccess.jsp").forward(request, response);
     }
 }

2、使用commons-fileupload完成文件上传

 package test_servlet_package;

 import java.io.File;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.Iterator;
 import java.util.List;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.apache.commons.fileupload.FileItem;
 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
 import org.apache.commons.fileupload.servlet.ServletFileUpload;

 public class test_servlet extends HttpServlet {

     String tempPath = "D:\\test";
     String filePath = "D:\\filePath";
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
         res.setContentType("text/plain;charset=gbk");
         PrintWriter pw = res.getWriter();
         try {
             DiskFileItemFactory diskFactory = new DiskFileItemFactory();
             // threshold 极限、临界值，即硬盘缓存 1M
             diskFactory.setSizeThreshold(4 * 1024);
             // repository 贮藏室，即临时文件目录
             diskFactory.setRepository(new File(tempPath));
             ServletFileUpload upload = new ServletFileUpload(diskFactory);
             // 设置允许上传的最大文件大小 4M
             upload.setSizeMax(4 * 1024 * 1024);
             // 解析HTTP请求消息头
             List<FileItem> fileItems = upload.parseRequest(req);
             Iterator<FileItem> iter = fileItems.iterator();
             while (iter.hasNext()) {
                 FileItem item = (FileItem) iter.next();
                 if (item.isFormField()) {
                     System.out.println("处理表单内容 ...");
                     processFormField(item, pw);
                 } else {
                     System.out.println("处理上传的文件 ...");
                     processUploadFile(item, pw);
                 }
             }
             pw.close();
         } catch (Exception e) {
             System.out.println("使用 fileupload 包时发生异常 ...");
             e.printStackTrace();
         }
     }

     // 处理表单内容
     private void processFormField(FileItem item, PrintWriter pw) throws Exception {
         String name = item.getFieldName();
         String value = item.getString();
         pw.println(name + " : " + value + "\r\n");
     }

     // 处理上传的文件
     private void processUploadFile(FileItem item, PrintWriter pw) throws Exception {
         // 此时的文件名包含了完整的路径，得注意加工一下
         String filename = item.getName();
         System.out.println("完整的文件名：" + filename);
         int index = filename.lastIndexOf("\\");
         filename = filename.substring(index + 1, filename.length());
         long fileSize = item.getSize();
         if ("".equals(filename) && fileSize == 0) {
             System.out.println("文件名为空 ...");
             return;
         }
         File uploadFile = new File(filePath + "/" + filename);
         File uploadFile2 = new File(filePath);
         if(!uploadFile2.exists()){
             uploadFile2.mkdirs();
         }
         item.write(uploadFile);
         pw.println(filename + " 文件保存完毕 ...");
         pw.println("文件大小为 ：" + fileSize + "\r\n");
     }
 }

3、依赖的jar：

 <classpath>
     <classpathentry kind="lib" path="base/WEB-INF/lib/commons-fileupload-1.2.2.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/commons-io-2.0.1.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/jsmartcom_zh_CN.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/mysql-connector-java-5.1.21-bin.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-compat-1.2.1.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-impl-1.2.1.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-jstlel-1.2.1.jar"/>
     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-spec-1.2.1.jar"/>
     <classpathentry kind="output" path="base/WEB-INF/classes"/>
 </classpath>